35mm versus medium format film: a practical comparison
The question of which film format to use comes up regularly when clients add a roll to their session. The answer depends on what the images are for and what quality of image you are after. This is a straightforward comparison of the two formats Susan uses at the studio.
35mm: the working format
35mm film gives 36 exposures per roll. The frame is 24x36mm, which is the same size as a full-frame digital sensor. The grain at ISO 400 is visible but not intrusive, and the format is versatile enough to work in most lighting conditions.
The cameras are lighter and quieter than medium-format bodies, which matters in a portrait session where the camera should not be the most noticeable thing in the room. Susan uses a 50mm and a 85mm prime lens on 35mm, both of which produce a natural perspective on a face.
Medium format: the slower option
The Mamiya RB67 shoots 120 roll film, giving 12 exposures per roll on a 6x7cm negative. The negative is roughly four times the area of a 35mm frame, which means more detail and a different tonal quality, particularly in the mid-tones.
The depth of field at equivalent apertures is shallower on medium format, which produces a more pronounced separation between subject and background. This is not always desirable, but for single-subject portraits it often is. The camera is large and deliberate. Each frame takes more thought, which changes the rhythm of the session.
Which to choose
For most portrait add-ons, 35mm is the more practical choice. It gives more frames, works in lower light, and the results are easier to predict. Medium format is worth considering for outdoor sessions in good light where the client wants a particular quality in the final images.
Susan will discuss the options before the session day. The film add-on is £95 per roll for either format, developed and scanned at the studio.
Both formats are tools. The choice is worth thinking about, but it is not the most important decision in a portrait session.